Lighting fixtures may be used to communicate between each other, or with other elements in a system. One way of communicating with such fixtures involves the use of Visible Light Communication (VLC) or other free space optical communications, such as infra-red and/or ultra-violet communications. Light bulbs utilizing LED elements and the increasing use of such LED light fixtures have provided additional opportunities for the use of VLC for the purposes of programming and control and communication.
For example, VLC and similar techniques might be used for commissioning or programming various fixtures in a system. In the lighting industry, it is desirable to ensure that all installed lighting fixtures or elements, such as within a building, are controlled as desired. When a lighting system is activated, it is tested and the control circuitry for the system is programmed and calibrated to ensure proper operation. The term “commissioning” is often used to describe such system activation, programming, calibration, and testing. For the purposes of commissioning, it is desirable to communicate with the various light fixtures and the control circuitry for the fixtures for the purposes of programming and controlling those fixtures to operate according to system parameters and control programs.
Existing VLC systems use fixtures wherein the entire fixture is implemented or affected for providing VLC. For example, some VLC systems have fixtures that will switch an entire LED diode string or array, i.e., every element in the array, in order to provide the modulation light output necessary for VLC. As such, existing VLC system designs and fixtures also must modify the entire power system and driver for a fixture to modulate the entire diode chain in the light fixture. Such control introduces complexity into a fixture, as well as increased expense. Additionally, separate power supplies or power transistors may be necessary for such VLC operation, involving expensive and independent power supplies and control circuits. Such complicated systems may also detrimentally introduce more heat into the fixture, that then has to be addressed.
The present invention is directed to providing VLC and free space optical communications in a low complexity and low cost embodiment. It is further desirable to introduce VLC capabilities into fixtures within a pricing range that was not possible in the past. Furthermore, it is desirable to enable such VLC without detrimentally affecting the overall illumination process of the fixture.